/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.iterate;

import java.sql.SQLException;
import java.util.List;
import org.apache.phoenix.compile.ExplainPlanAttributes.ExplainPlanAttributesBuilder;
import org.apache.phoenix.schema.tuple.Tuple;
import org.apache.phoenix.util.SQLCloseable;

public interface ResultIterator extends SQLCloseable {
  public static final ResultIterator EMPTY_ITERATOR = new ResultIterator() {
    @Override
    public void close() throws SQLException {
    }

    @Override
    public Tuple next() throws SQLException {
      return null;
    }

    @Override
    public void explain(List<String> planSteps) {
    }

    @Override
    public void explain(List<String> planSteps,
      ExplainPlanAttributesBuilder explainPlanAttributesBuilder) {
    }
  };

  /**
   * Grab the next row's worth of values. The iterator will return a Tuple.
   * @return Tuple object if there is another row, null if the scanner is exhausted.
   * @throws SQLException e
   */
  public Tuple next() throws SQLException;

  public void explain(List<String> planSteps);

  /**
   * Generate ExplainPlan steps and add steps as list of Strings in planSteps argument as readable
   * statement as well as add same generated steps in explainPlanAttributesBuilder so that we
   * prepare ExplainPlan result as an attribute object useful to retrieve individual plan step
   * attributes.
   * @param planSteps                    Add generated plan in list of planSteps. This argument is
   *                                     used to provide planSteps as whole statement consisting of
   *                                     list of Strings.
   * @param explainPlanAttributesBuilder Add generated plan in attributes object. Having an API to
   *                                     provide planSteps as an object is easier while comparing
   *                                     individual attributes of ExplainPlan.
   */
  void explain(List<String> planSteps, ExplainPlanAttributesBuilder explainPlanAttributesBuilder);
}
